I'd like to propose an idea - I'm not saying it's a
good idea, just an idea.
Rather than incorporating "datasets that provide good unbiased definitions of these terms that candidates use", allow users (ideally quality controlled in some magical way) to annotate specific words and phrases, and attach comments to them (like: "We will stop the radical indoctrination of our students and restore patriotic education to our schools." What does "racial indoctrination" refer to? What does "patriotic education" refer to?) This would then make the site not just a useful informational tool, but also add a social media meta-conversation type of layer on top - in the case of the above comments, revealing to other users the vacuousness of political rhetoric, which a lot of people seem to take at face value, as a sincere and honest representation of true (as opposed to truthy) intent. Politics is largely disingenuous theatre imho, I think it would be healthy for this to be pointed out to people more often.
Obviously, there are all sorts of problems with this, one of which is that cynical people like me would use it for shitposting and that sort of thing. To that, I would suggest forcing a user to choose some sort of a ~perspective from which they are posting, and to be honest and take things seriously (and enforce this with an iron fist) - so in my case, I would often choose "Hyperbolic Cynicism" and treat the whole thing like the mockery that I perceive it to be (here I mean: both candidates, and the entire system). And other users could have the option of filtering out idiot comments like mine (or, choose to only see comments of this kind, or whatever the individual prefers).
And then in addition to speeches, you could also host various news articles, and let people do the same thing. Yes, there is noteworthy overlap with Reddit and many other sites, but there's also plenty of leeway for significant differentiation.
Of course, this would significantly change (and add risk to) the nature of your website, so perhaps you could do a completely different, renamed/unaffiliated version of it and tries this angle out.
Anyways, just an idea. Overall, I think it's a good idea and really nicely done, good job.